This invention relates to compositions and methods of using the compositions in preparing ferrous metal components for subsequent surface electroplating by preparing a dispersion containing an acid and a sequestering agent, immersing the components and abrading media in the dispersion, and agitating the components and the abrading media while maintaining the components and the media immersed in the dispersion. Similar technology has been known heretofore from such disclosures as Hays U.S. Pat. No. 2,890,944; a series of United States Patents to Herman Ben Snyder including U.S. Pat. Nos. 2,940,838; 2,981,610; 3,052,582; and 3,061,494; and Michaud et al U.S. Pat. No. 4,491,500.
In accordance with the improvements of the present invention, the compositions used are liquid dispersions. In liquid form, the composition has, by weight percent excluding any water content; up to about 20% oxalic acid; up to about 50% of phosphorus sequestering and buffering agents; the ratio by weight of oxalic acid to phosphorus agents being in a range of from about 0.70:1 to 0.20:1 and preferably such as to provide a composition pH in a range of from about 3.5 to about 7; an amonifying agent; a surfactant; and a suspending agent sufficient and effective for enabling the suspension of the constituents in water so as to form the composition.
It has been known heretofore in the manufacture of ferrous metal components that electroplating of such components may serve the dual functions of protecting the ferrous material against rust or other deterioration and enhancing appearance. For such reasons, it is commonly done to plate hand tools such as wrenches and the like with bright electroplate finishes. In preparing components for such finishing. It is important that the surfaces to be plated have a certain degree of smoothness for appearance sake, and sometimes important that they be polished. While such polishing has been done in a number of different ways, chemical processes for metal removal have achieved some success and acceptance, and have followed generally the teachings of the prior patents listed above.
In processes of the type described, there is a constant balancing of harshness against productivity. In attempts to achieve high productivity of components and short cycle times for the use of equipment, some users have attempted the use of strongly acidic solutions. In attempts to achieve desirable surface finishes, other users have attempted the use of less acidic dispersions. In both instances, problems may be encountered with exhaustion of dispersions used and effluents created. Attempts at prolonging the usefulness of solutions have involved the use of sequestering agents to assist in avoiding exhaustion.